THE SEVENTY-TWO-YEAR-OLD Japanese director Shohei Imamura’s studies in aberrant humanity have been nothing if not singular. The Eel (1997) was undoubtedly the best film ever made about a man’s near-cosmic oneness with his pet fish, and Imamura’s latest, Dr. Akagi (which opened in mid-January in New York), is more accomplished still: It’s the winningest comedy of all time . . . about hepatitis. The title character (fervently played by Akira Emoto) is nicknamed “Dr. Liver” because he diagnoses disease of that organ in virtually every patient he treats. We first catch sight of the doctor in an immaculate white suit, chasing an uncooperative patient along the beach. Akagi is a walking (or rather running) sight gag who looks like he should either be holding a butterfly net or have one thrown over him. But it’s 1945, hepatitis is pandemic, and the explosion from nearby Hiroshima will soon enough